Loud speaker



Patented Nov. 10, 1925.

N 'r I 1,560,925 PATENT! OFFICE.

DELMAR A. WHITSON, OF 140% ANGE'LES, CALIFORNIA, ASSIGNOR, BY lllESNE ASSIGN- MENTS, TQ EE'IJENTORPHONE COMPANY, 013 LOS ANGELES, CALIFORNIA, A COBFOJRA- TION OF CALIFORNIA.

noun srnannn.

Application filed August 30, 19%. Serial No. 585,159.

To all whom it may concern:

Be itknown that l. DELMAR A. "Wrrrrson,

deliver a magnified volume of sound. Re

ceivers of this character are commonly called loud speakers and have their particular application in the art of radio telephony in which they are employed with receiving sets for the purpose oi making the sounds trans mitted by radio audible to persons situated at a distance from the device, thus making it possible for a large nuinbpr of persons to hear broadcasted material received by a single set.

It is an object of the invention to provide a ,loud speaker which'may be constructed and distributed at a low first cost owing to the simplicity of the construction thereof.

It is a further object of the invention to provide a device of this character which will deliver sound amplifications which may be heard throughout an ordinary sized room or which may be adjusted to modulate the sounds delivered thereby by varying the strength of th exciting circuit.

lit is an object of the invention to provide in this simplified form of device a diaphragm having connection with a magnetic vibrating means consisting of an armature in which magnetic fluxes are maintained in constant balanced relationship when not influenced by the exciting magnetism. so that residual magnetism is not built up within the armature. I

It is a Further obiect ot' the invention to provide a. simplified torm of construction in which the operating elements of the device are mounted upon the underside of a cover plate and are removable therewith from the shell. and are therefore easy of access for adiustment.

'l he specific advantages ot the invention and further obiects thereof will be made evident hereinafter.

llet'erring to the drawing which for illustrative purposes only,

Fig. 1 is an elevational view, drawn to till a small scale, showing a loud speaker of my invention having the amplified horn thereof in place ready for use.

in Fig. 2 is an enlarged vertical sectional. view through the loud speaker shown in Fig. 1 but with the amplifying horn removed therefrom.

Fig. 3 is a section taken on a plane represented by the line 3 -3 of Fig. 2.

Fig. 4; is a schematic diagram illustrating the principles involved in my invention.

As shown in the drawing I provide a shell 11 mounted upon a base 12 and having a cover member 14- which fits into the top thereof. The shell ll is cylindrical and the cover member 14 is also of cylindrical formation, thus adapting it to facility in performing machine operations. The member 14 is provided with an upwardly extending central projection 15' provided with an opening 16 adapted to receive the lower end 18 of an amplifying-horn 19. In the underside of the cover 14 a shallow stepped circular recess 20 is formed, having central communication with the opening. 16. Across the recess a diaphragm is secured by a ring member 26 whichat'taches to the underside of the cover member 14 by means of screws 28. I

Upon the undersideof the ring member 26 I mount a small U shaped magnet 30, this magnet beii'ig provided with downwardly extending poles 31 and 32. Beneath the magnet and preferably in the same vertical plane therewith, as shown, apermanent ma net 35 is placed with the poles S6 and 'lpipwardly directed, the pole 36 being shouldered as indicated at 38, andattachment thereof made with the pole SI of .0 the magnet 30 by means of a screw 40. The pole 37 of the magnet 35 is supported by a brace 39 which is attached also to the ring 26. The poles 32 and 37 are beveled off as indicated at 42 and a gap is provided there-' between through which an armature 45 ex- 100 tends. This armature 45 is flexibly secured to the end of the pole piece 31 by means of a screw 47 and has an exciting coil 48 mounted therearound, this coil being situated between the poles of the magnets, as

shown in Fig. 2, and having a central tube l9 through which the armature 45 extends. The free end 48 of the armature 45 is con- "treated by a link member 4.9 with the center 5!) of the diaphragm 25. i

As indicated in 4c the magnets and are so mafliiccizcd and placed chat the north pole 0 each magnet is adjacen'c to time south pole of tho other magnet, thus creating s magnet struciurc in which a free circuiious ilow of magnetic flux may pass. 'lllic course providcd for the flow of magnetic flux is continuous except for the nicer posiiion of the 55. The exciting coil :3 surrounds the body of the urma'iurc and is cucrgized ilirougli leads 57 and 58 which are connected with a suiiablc rcceiving sci.

ll; will be pcrccivccl that Whenever a curram is flowing through the coil ll) a mugnclzic liux will be impressed in dis armature 45, this flux having a polar-it depending upon the rlircciion of flow of foe exciting current. lit "ill lsc seen that if the direction of current is such film-i: the forward end 48 of? the armaiurc is given )ositivc polarity, the armature will be XPQLEd by the north pole of line niagucifl and attracted by lllQ souili polc oi the magnet 30 thereby pro luclog a combined actionof forces upon the armature co cause its upward movement and ilic upward movement of ilic dia 'ilirugm ii virtue of the conncciion tlicrcivilili of ilic link &9 which connccis between illiL (liapliramu and the cud 48 of the armature. movzilulc in tlic ilanc of the n'iagzncts.

An essential 'cuturc of my invention rcsides in the. manner in which the magnetic field provided by the magnets 36 and is short-circuitcd by the armature so ilial; a flow of magnetic fluxcs fakes placc as indicaiccl loy the arrows 60 and 61, These countcuflowing fluxes preserve a balanced siace of magnetism in tile armature which opposes the collection of residual magnetism therein due to the activating magnetic flux created by the cncrgizat-lon of ihe exciting coil 48, and further assists in clearing Whatever slight amount of residual magnetism may take place in the armature due to the energization of the coil 48. in this mannor am able to provide a verysimplc equipment which is susceptible to rapid vibrations which, losing free of residual maguciic iiifinences, delivers a faithful sound reproduction.

it "will be perceived that in ijl'le construcion or she shall and the cover, ii: is possible to remove Elie entire mechanism from the shell by simply lilting iii'lf; cover therefrom, films making it a very simple malier to make any necessary adjustment.

1' claim as my invention:

1. "In a loud s cakcr ilic combination of: :1 pair of dcpen ing magnets placed in sub stantially the same vertical plane and with filie posicivc pole of each magnet adjaccnl: to ltl egriicgativc pole of ills other inagncis, a positive pole of one of said ma ncts being diroctly in contact will a negative pols of tile ollicr of said magnets; on armature hav ing cud secured to one of said magnets and time other end thereof amending between the negative pole of onc of said magncts and the positive pole of the other ofsaid magnets; an exciting coil surrounding said armature-for creating a flow of magnetic flux therein luirin a density corresponding: to the strc'ngtlioi current flowing through said coil; a diaphragm; a shell surrounding said magnets? link means for imparting tlic movement; of said armature to said liuphragm: and incaus for supporting said (liaipliragiii horizontally at the top of said shell.

2. In a loud speaker, the combination of: a pair of vertically aligned magnets placed with the positive pole of each magnet adjacent to the negative pole of the other magnet, a positive pole of one of said magnets being directly in Contact with a negative pole of the other of said magnets; an annaturc having: one end thereof between a negative pole of one of said magnets and a positive pole oi"? the other of said magnets; an exciting coil surrounding said armature for creating a flow of magncnio flux therein having a density corresponding to the strcngili of currcnl; ilmviug through said coil; a shell surroimdin said magnets and provided with a covcf; a diaphragm; linll means between said diaphragm and said armature for imparting inc movement of said armature to said diaphragm; and means for supporting both said diaphragm and said magnets from said cover.

ln 2'- loud speaker, the combination of: a magnet structure providing a circuitous flow of magnetic flux, said structure having a gap tl'icrcin; an armaturc having one on thereof situated in said gap in said magnet structure and having the other and thereof in cngagcmeni with said magnetic structure a point opposite to said gap; an exciting coil surrounding said armature for creating a flow of magnetic flux therein having a density corresponding to the strength of current flowing through said coil; a diaphragm; a shell surrounding said magnets and provided with a cover; link means for imparting the movement of said armaturc to said diaphragm; and means comprising a ring" supporting both said diaphragm and said magnets from said cover.

4. in a loud speaker, the combinalsion of: a shell; a substantially vertical magnet structure suspended within said shell and providg mg a circunous flow 01. magnolia flux, said slruclurc having agap tlicrein; an armature having one end thereof situcced in said gap in said magnet simcturc and having the other end itiicreof in engagement with said magnetic structure a pointoppoaicc to said ,i ap; an exciting coil surrounding said armature for creating a flow of magnetic flux. iherqin having a density corresponding to ill? ion

gthe strength of current flowing throu 11 said 55,0011; a diaphragm supported Within the jupper part of said shell; and link means he- 'twecn said diaphragm and said end of said armature for imparting the movement oi said armature to said diaphragm. i

5. In a loud speaker, the combination of: a pair of magnets placed with the positive pole of each magnet adjacent to the negative pole of the other magnet, a positive pole of one magnet being attached to the ne ative pole of the other magnet, and a gap eing provided between the other negative pole and the other positive pole; an armature having one end thereof dis osed in said gap and the other end thereof iibxibly supported at the joining point of said magnets and against an end-of one of said magnets; an exciting coil surrounding said armature for creating a flow of magnetic flux therein hav 'ing a density corres ending to the strength of current flowing t rough said coil; a diaphragm; and link means for imparting the movement of said armature to said v diaphragm.

6. In a loud speaker, the combination of: a pair of magnets placed with the positive pole of each magnet adjacent to the negative pole of the other magnet, a positive pole of one magnet being attached to the ne ative pole of the other magnet, and a gap eing provided between the other negative pole v and the other positive pole; an armature having one end thereof disposed in said gap and the other end thereof exibly supported at the joining point of said magnets; an exciting coil surrounding said armature for creating a flow of magnetic flux therein having a density corresponding to the strength of current flowing through saidcoil; a dia throu h said cover situated suhstantiaily contra ly of said recess; a diaphramn across said recess; a ring member secnrdhle upon the underside of said cover for holdin said diaphragm across said recess; a iii-s aped till magnet secured upon the underside of said ring member, with the poles thereof extended downwardly; a U-shaped magnet moiinted upon said ring member beneath said first named magnet, and with the poles thereof directed upwardly, the negative pole of one of said magnets being secured to the oertive pole of the other of said magnets, there being a gap between the other said positive and negative poles of said ma, eta; an armature flexibly attached to and first magnet at the .point at which said magnets are joined, and extending horizontally through said gap; an eircitinn; coil for creating a flow of magnetic flux in said emitters; and a link extending between the movable end of said armature and the center of said diephragm for transferring the movement of said armature to said dia hragni.

In testimony whereof, have hereun o set my hand at Los Angeles, California, this 16th day of Au mst 1922.

detains nvtnrrson 

